Focus or Tracking issues

[drumsolo]

Hi guys,

I have returned to this magnificent hobby after 5 years and hoped to pick up where I left of although it seems I had forgotten a lot!

Anyway I took some pics of Orion Nebula  the other night and managed to get my auto guider working as well. I took 4 minute subs but the results are disappointing, they wouldn't stack in DSS and look blurry to me. I did use a Bhatinov mask to focus on a star first before imaging. Does this image look like a focus issue or tracking or both as the stars down the bottom looked like trailing slightly. I also used a coma corrector with an IDAP LP firer, could this combo have caused any issues?

Grateful for assistance to as I really want to get imaging again to a good standard.

Thanks!

Stuart

[Freddie]

Look closely and you will see that every star is a double. It looks as though the mount jumped slightly mid exposure rather than being a constant drift through the whole exposure.

[paul mc c]

Are you guiding your mount?

[vlaiv]

Both.

[drumsolo]

I am worried that I may have damaged the mount gears as when I was setting up I forgot to put the weights on before I slewed the scope and it made a horrible crunching sound. Can the gears be replaced if they are damaged?

[drumsolo]

Also when i was guiding use orion starshoot and PHD the picture from the starshoot started showing trails rather than round stars , does this also point to mount gear problems?

[wimvb]

When you get the chance, open your mount to inspect the gears. Just take the cover off on the side of the mount. Make sure the gears mesh without binding. Also slew the mount one full rotation in ra and dec without any load. If it runs smoothly, with no more grinding than usual, you're probably ok as far as the mechanical part is concerned. While you have the mount open, check also for backlash.

The image shows both poor focus and tracking issues. The focus lock screw can cause focus shift, so always check focus after you lock it. A motorfocus will "lock" on its stall torque, and you don't need to use the lock screw.

Once you have checked both these things, you can expect better results.

[drumsolo]

Thank you so much for your advice, I will take the cover off and have a look. If the gears are binding then I assume I can buy replacements gears?

What do you mean by backlash?

Never heard about 'Motorfocus', is that something I can replace on my sky watcher 200P?

Thanks again 

[wimvb]

1 hour ago, drumsolo said:

Never heard about 'Motorfocus', is that something I can replace on my sky watcher 200P?

https://www.firstlightoptics.com/skywatcher-focusers/skywatcher-auto-focuser.html

[don4l]

9 hours ago, drumsolo said:

I am worried that I may have damaged the mount gears as when I was setting up I forgot to put the weights on before I slewed the scope and it made a horrible crunching sound. Can the gears be replaced if they are damaged?

I did something similar once with my EQ6, and there was a terrible noise -so possibly the same as you describe.  There wasn't any noticeable damage.  The noise sounded like the mount had destroyed itself.  With hindsight, I suspect that the motors make an awful noise when slipping, but noo damage is done.

I definitely wouldn't attempt to take it apart unless I was certain that damage has occurred.

 

[wimvb]

9 hours ago, don4l said:

I definitely wouldn't attempt to take it apart unless I was certain that damage has occurred

Checking the motor gear only involves opening the cover, and giving the gears a wiggle. That will show if they mesh ok, and reveal any damage. It's the equivalent of looking under the bonnet. I agree with not doing any further dismantling unless absolutely necessary. 

[Owmuchonomy]

The grinding noise is the clutch taking effect.  This is most likely down to poor balance set up of your equipment and/or too tight an adjustment on your worm drives(s).